By Kim Bunker

The strength of the piano structure is very important to help control tuning stability. Each string (about 230 strings in a piano) has up to 180 pounds of tension. This amounts to approximately 20 tons of tension or the combined weight of 9 (nine) full size automobiles when the piano is in tune. The tension must be supported by the back frame construction (a combination of the metal plate and back posts). The stronger the back frame, the longer the piano will stay in tune.

Full vertical cast plate Grand piano plate


The plate should be what is know as "full cast plate made of gray iron and showing the name of the piano manufacturer cast therein. Finish should be either bronze or silver. The tension must be supported by the back frame construction (a combination of the metal plate and back posts). The stronger the back frame, the longer the piano will stay in tune. There are many fine European and American pianos that have no back posts at all. This is because they place an emphasis on the strength of an extra heavy I-Beam like plates. Both methods are excellent.


1. A piano is a stringed instrument.
2. Strings are pulled to high tension. At A-440 pitch per string the pressure is 140 lbs
3. The back posts and the cast iron plate work in concert to support the tremendous tension of the strings.
4. Reasons why it is necessary to have the strongest structure possible to support string tension:

* To prevent the back of the piano from warping and twisting.
* To enable the piano to stay reliably in tune between tunings.
* Without solidity in the structure the many parts of the piano could not function properly.

Vertical backpost construction


1. Look at the back of the piano first, the back posts are easy to see on most instruments. Notice the following things about the back posts:

* Size of the post; not only width, but depth.
* Double, triple, posts - wood grain appearance
* Post extend to the top of the piano.
* Posts extends to the bottom in a tight tension and mortise construction. Feel with fingers.


* Because its the strongest wood for it's weight.
* Resists splitting and cracking.
* Spruce's lengthwise grains are straight,
close and dense which provides rigid support.
* Posts are bolted to cast iron plate.


As mentioned, few pianos will have metal backpost's, others, will have virtually no wood backpost's at all. Many high quality pianos have scale designs which provide plates that have rigid I - Beam like construction that extend to all four corners of the frame, which actually adds the strength of two or more backpost's. This is an expensive process known as a full perimeter plate. This is an acceptable method.


1. The purpose of the pin block is to firmly hold the tuning pins in place where the strings are attached.

* Tuning pins vary in quality.
* Better grades of tuning pins have machine cut threads that are cold rolled. This process creates a reverse lock effect which helps greatly in tuning stability.
* Tuning pins should be "blued steel", an electronic method to prevent rust.
* Nickel-plated steel tuning pins are even better then blued pins.

2. The pinblock in many of the finest pianos in the world consists of several plies of hard rock maple. Alternate plies have grain running at ninety degrees to that of adjoining plies to assure even gripping of the pins, and to prevent splitting of the pin block.

* Material of pin block should be hard rock maple.
* Wood should be quarter sawn for strength.
* Pin block should be at least 2" thick.
* Number of plies not as important as type and construction

Vertical Piano Hammers;



This is another area where you can visibly see quality. Are the hammers nicely spaced? Are they all in line? Ask the salesperson about the hammer weight. Good pianos in a console size use about a ten to twelve pound hammer. Piano hammers are made of fine wool felt which is formed around a hard-maple hammer molding. First-grade piano hammers are made of two layers of felt; the outer layer is white, the inner usually purple, green or magenta.

The layers of felt are applied separately. The forming and gluing of the felt to the hammer is done with tremendous pressure applied by hammer presses. Many tons of pressure are applied from several angles, forming the shape of the hammers.

The result is one long piano hammer which is then cut into individual heads. Holes are bored at the proper angles on the underside of each head, into which the hammer shanks are later glued. Each set of hammers is then individually and painstakingly fitted to the piano. Some hammers are stapled, others have a T pin cotter key-like wire through the hammer to insure stability in the hammer. Many imported pianos have hammer weights of up to twenty two pounds on grand pianos.

One of the least understood and most controversial subjects in the world of pianos is hammer weight. The prospective buyer is told that one piano has twelve-pound hammers, while another has only nine or ten-pound hammers. A glance into the piano tells us that surely those hammers, even all eighty-eight of them, do not weigh from nine to twelve pounds.

The figure refers to the size of the felt sheets used in the making of the hammers. The felt in an individual hammer averages 109/l000ths of an ounce, depending on the weight of the sheet of felt from which it was made; and the difference between nine and twelve-pound hammers average 36/l000ths of an ounce per hammer.

The important thing to remember about hammers like all other parts of the piano, is that not only the quality of the materials, but how those materials are utilized in the building of the instrument determine the overall quality of the product. In the case of hammers, the proper shape and hardness are the key factors affecting proper tone regulation. That's why it is often said that while a good hammer can't make a poor piano sound good, a bad hammer can spoil the best piano.

Like the speaker of a radio, a piano's sounding board is a vibrating diaphragm. To work properly, the board must always be under tension. This is accomplished by having the center of the board arched, or crowned, with the strings pressing down on the board where they cross the bridges. The vibrations of the strings are thus transmitted through the bridges to the sounding board, where they are greatly amplified by the board and projected into the air to reach our ears.

The piano string acts as a tone generator. The sounding board's function is to truly reflect and amplify that tone. The sounding board is the most important single part in the piano because if the board is bad, you do not have a piano until there has been a major repair job. No real music can come out of a conventional piano except through the sounding board. So that it will vibrate freely, a sounding board is necessarily a very thin panel, usually from 3/16 to 3/8 of an inch thick. Ribs are added to stiffen the board and to help preserve the crown. The reason the ribs are shaped at the ends is to allow the board more flexibility around its perimeter. Until recent years, all piano sounding boards were made of solid lumber pieces glued edge to edge. Wood, however, has an irresistible tendency to absorb or lose moisture according to the humidity content of the surrounding air. Absorption of moisture causes the conventional sounding boards to expand, increasing the tension of the strings and, thus, raising the pitch. Conversely, the pitch is lowered when the board dries out. It has been a constant struggle to try to keep such sounding boards from splitting or from losing their all-important crown. To obtain perfect musical results, there must be good contact between each of the strings and the board. This perfect contact cannot be maintained if the board loses all, or even part, of its convex form (crown). Piano sounding boards are made of wood because no other known material amplifies musical tones so well.

We use the Finest Grade Solid Copper Wound Bass wire and the Treble wire as shown below is Mapes "Strike Gold" Stainless Swedish Steel wire;


Every musical effect in a piano must originate in the strings. The soundboard, no matter how perfect, can only amplify the sound produced by the strings. Pianos have from 215 to 230 steel strings graduated in length and thickness to produce the 88 notes of a piano's scale design. The shortest string is about 2", the longest string may be 84" or longer.

The bass strings should be pure copper wound, not plated.

* Examine the spacing of the strings in
relation to other strings, spaced evenly
without touching another string.

* Depressing a key slowly, check damper
alignment. At the same time, check as
hammer strikes the strings.

Check to see if hammers strike all of the strings of all notes.

Inspect the strings for even spacing (not touching another string) and proper alignment with the dampers.

Listen to the piano - Is the tonal output powerful enough, at least impressive enough that you should expect from a "classic" piano, but
capable, nevertheless, of filling a room no larger than 15 square feet or of a volume not more than say, 2500 cubic feet ?

Is the tonal output reasonably mellow (very bright indicates hardened hammers from age or dry climatic conditions).

Is the tone even and with a fair singing quality ?

Is the action satisfactory, that is, does it give a fairly elastic response to your touch ?


Vertical action being assembled


Briefly stated, the way a piano action works is that the down pressure on a key is converted to a forward motion of the hammer towards the strings. The hammer travels five times as far and approximately four times as fast as the front end of the key does, the key travel being only about 3/8 of an inch at its front edge. This is accomplished through a remarkable system of levers and pivots which, for a quality piano, must be adjusted to the utmost accuracy, making the action so responsive to the player's touch on the keys that there is almost no limit to the musical effects obtainable. For a better, more natural leverage, piano keys slope slightly downward towards the back and become level when the key is depressed.

A piano action would be a fairly simple mechanism if, when you depressed a key, it just had to push the hammer against the string. But if it worked that way, there would not be much tone because the hammer would stay against the string and, acting as a muffler, would stop it from vibrating. Thus, it would not have had time to return to its starting position after you released it.

Consider the manufacturing problem created by the fact that thousands of the parts in a piano are moving parts, that many are very small and that on some of them a variation of a thousandth of an inch will affect their performance. Not only is the utmost precision required in making and assembling the parts, but they must operate quietly and resist friction, wear and loss of accuracy under long and strenuous use. The materials used today for the best piano actions are largely wood, felt, woolen bushing cloth and leather. Like all products of nature, these items are inclined to be unstable when exposed to varying climatic conditions, although this hazard is greatly reduced in the better pianos by use of the highest quality materials and by superior workmanship.

If metal could be used, it would simplify the manufacturing problems and substantially reduce the cost; however, metal (not being noiseless without frequent lubrication and adjustment) does not lend itself to the purpose and very little of it is employed. Many other materials, including all kinds of synthetics, have been tried, but, with few exceptions, have not proved success, imagine a hinge or bearing that would work smoothly and silently for fifty years or more without lubrication or constant adjustment. Every pivot in a piano action must do this and they do it because these moving parts are held in a circle of specially made material called bushing cloth. Action hinges or pivots are made by boring holes in wooden parts, lining the holes with this bushing cloth, then connecting the adjoining parts with German Silver center pins which will rotate in these cloth bearings indefinitely without attention unless exposed to the most abnormal climatic conditions. This cloth, among its many other properties, must be uniform in thickness to an unbelievable degree. The makers allow a tolerance of 2 one-thousandths of an inch, plus or minus, which is less than one-half the thickness of an ordinary business card and is an incredible measurement for such material. It requires a total of ninety-six different operations in the felt mill to produce the superior grades of this cloth used in actions.

To summarize the story about piano actions, good performance is not only a question of superior materials. but also involves skill, experience and the willingness of the piano manufacturer to spend the extra money to have these important hidden parts as accurate and dependable as it is possible to make them.

Soundboard & Bridge;

1. The soundboard consists of a sheet of wood;

* One thickness spruce (the term "solid" when referring to spruce soundboards is very often misleading today because some builders of pianos with laminated boards where all three layers are spruce, refer to soundboards as "solid" spruce meaning they are all spruce).
* Special taper. Starting from 6 to 9mm at the at edges (three eighths of an inch thick and beveled) as a resonator.

2. The soundboard is not flat as it appears. but has a crown held in place by a series of ribs. If the soundboard were flat or if it were to lose this crown, there would be very little volume or tone.

* The ribs are made of a lightweight wood such as sugar pine, are double notched and fitted into soundboard lining. * They are tapered to fit and correspond with the taper of the soundboard.

3. Bridges, made from maple, must be planed to exact thickness from end to end, so as to provide the proper down bearing of the strings upon the bridges, this is measured by the use of a "bearing gauge" (See Glossary of Piano Terms).

* Bridges are glued and further secured to the soundboard.
* To prevent vibrations bridges are secured with wood screws that have maple buttons under their heads.
* Bridges are double notched.
* Bass bridge cantilevered.


From an article by Dr. William Braid White,
Principal of the School of Pianoforte Technology, Chicago, Ill., reprinted from the Piano Trade Magazine, Chicago, Ill.

"IN THE PIANO the function of the soundboard is to take up and repeat the vibratory motions of the strings, and thus to set up in the air sound waves of vastly greater size and power than could be generated by the strings alone. The more faithfully the sound-board performs this function, the better soundboard it is. The layman will better understand this amplifying function of the soundboard if he will think of the relatively enormous area of the board when compared with the very small area of all the strings taken together. Hence, when the piano is played, the soundboard, repeating the vibratory motions of the strings, sets in vibration vastly more air than could the strings themselves.

The more than two hundred strings that constitute the tone-generating element of the piano are stretched, at high tensions, over wooden bridges, or supports, which are rigidly fastened to the surface of the soundboard. Thus, within a small fraction of a second any motions of the strings are transmitted through the bridges to the soundboard, which as it were, accepts them, and faithfully reproduces them over its entire surface. These tiny but intensely complex motions, originating at the strings, are transmitted to the large body of air surrounding the front and back surfaces of the soundboard, thereby setting up powerful sound waves which immediately register on the ear-drums of all within hearing.

So faithfully does the sound. board perform this difficult function, that no matter how many strings may be sounding at one time, their almost incredibly complex motions will always and un-failingly be taken up and reproduced. Thus, the soundboard of the piano acts just as does the parchment head of a drum or the thin steel diaphragm of the receiver element in a telephone. It should be remembered, however, that it is the strings, and not the soundboard, that originate, by their vibratory motions after they have been struck, the sound which the soundboard amplifies.

In order to obtain these very remarkable effects of amplification, the soundboard of the piano must be constructed with exquisite skill. Its length and breadth depend of course, upon the size of the instrument, while its thickness, with some variations between one end and the other, averages one-quarter inch. The pieces of spruce wood from which it is made are matched in such a way that the grain runs roughly parallel to the line of the great bridges upon which the strings rest.


It is strange but true that these simple facts about the effect of the strings upon the sound board and about the soundboard's responses to the strings, are still very little understood. Thus there persists a common notion that a crack in the wood must in some way cause a deterioration of the tonal output. Actually, no such effect is to be expected. The erroneous idea that a crack in a soundboard reduces the tonal output is undoubtedly due to the equally erroneous theory that sound "vibrations" in some way travel transversely across the soundboard. But, as has been shown here, the movement of the board is that of the movement of the strings, up and down in the case of a grand, backward and forward in the case of a piano of vertical construction. The glued-up strips of thin spruce, reinforced by bridges and ribs, which constitute the soundboard, become in fact a single unit, so that the whole board vibrates with the playing of even one single note anywhere in the scale.


For this very reason a crack or check in a soundboard reduces the soundboard's ability to amplify the vibrations of the strings only to the extent to which the crack reduces the vibrating area of the board.

Soundboard areas vary with the size of various pianos, but consider for example a board with an area of 4,000 square inches, counting both surfaces. Now assume that there is a crack in this board 35 inches long and one eighth inch wide, which would be an enormous crack. That crack would have an area (counting both surfaces) of 8 3/4 inches, and so would reduce the air disturbing area of the board by less than of one per cent, all amount utterly negligible. Here we have considered the effect of an enormously big crack. A dozen ordinary cracks, even if they extended from end to end of the soundboard, might have about as much effect, certainly no more. So long, in fact, as the structure of the soundboard re-mains solid, with ribs and bridges adhering correctly to the surface of the soundboard, and with the entire periphery rigidly fastened into the frame of the piano, the question of cracks is utterly unimportant. "

Dr. William Braid White


As a matter of fact, the tonal output of any piano, with no cracks in the soundboard at all, is subject to vastly greater change with every change in temperature and humidity. The alternate absorption and evaporation of moisture affects the soundboard, and therefore the tone of the piano, to a far greater degree than any crack or accumulation of cracks, yet few persons complain of this or even appear to notice it.

Wood is used for sounding boards because countless tests by several generations of piano builders and technicians using steel, aluminum and other materials proved that wood best reflects the tonal waves or vibrations transmitted by piano strings. Once this fact was accepted, it became a problem of how to make the wood "behave" so that the sounding board would approach being as durable as the rest of the piano instead of being one of its weakest parts.


The next step, and one of the most critical in the making of a fine piano, is the shaping of the treble and bass bridges. The bridges, of Northern hard maple, must be planed to exact thickness from end to end, so as to provide the proper down-bearing of the strings upon the bridges. It is this correct down-bearing which is so vital to the transfer of the string vibrations to the soundboard (resulting in pleasant piano tones).

Bridges should be glued to the sounding board with hot hide glue and further secured with wood screws from the back. Such screws should have maple buttons under their heads. The bridges must be accurately notched, at both top and bottom in the case of treble bridges, for each individual note. This provides for the "stopping" of the string at a precise point in much the same way as a violinist "stops" his strings be fingering. Bass bridges are planed on both edges for the same reason. If you notice most bass bridges are mounted like a diving board this is called (Cantilever) the principle behind this type of mounting is to create a fuller sounding bass.

A time and money-saving way to do this important bridge notching is to notch the treble bridge on the top edge only. Half the work, half the cost and many piano buyers can't tell the difference unless they are able to distinguish subtle differences in piano tone.

Solid Brass Vertical Piano Pedals;


Most piano manufacturers offer three pedals. On most vertical pianos the pedal to the right is a full sustain pedal and by depressing it, the piano tone will linger on or sustain the note. The left pedal is known as the "Una Corda", which softens or limits the power of the tone by moving the action forward and limiting the distance the hammers travel. On a grand piano it shifts the action slightly, enabling the hammer to strike fewer strings.

A third pedal in the middle varies from brand to brand. It may serve to sustain the bass notes only, or it may act as another form of soft. In some cases, it drops a piece of felt to provide a muffler, or practice pedal.

On a grand, it becomes a true "Sustenuto", that is, allowing the pianist to sustain many notes as long as the pedal is held. A good way to tell about the quality of a piano is to hold a pedal in your hand and get a feel for it. Twist it and push it, then go to a more expensive piano and compare. You'll see the difference in quality.

As a final point of clarification, many very fine pianos in the world only have two pedals, and for many years many American pianos including Steinway only used two pedals on many verticals. The center pedal on vertical pianos is an extra feature which can be a mute, a form of soft, or even a bass sustain. There is nothing wrong with having two pedals on a piano. For many years, that is all anyone had.


The case is made of veneers like Walnut, Mahogany, Oak, Pine, Maple, etc., It has a core made up of cross sections of another yet cheaper form of wood, usually Poplar and now coming for the Asia is Particle or Chipboard and even Pulp (multiple ply Paper) which are totally acceptable by today's standard because they are for cosmetic appearance only and should not wear out..

Next, is the beauty of case design and finish. The standard cases are and made or finished in mahogany, walnut, ebony, rosewood, oak, fruitwood, pecan or pine. The two first named are the more popular. All are dependable if the piano is well made. The manufacturing process for pianos does not readily lend itself to automation, due to variations in the acoustical qualities in pieces of wood. These variations require skill in selecting the wood stock and conditioning it to specific moisture levels. Many of the other labor - intensive functions such as voicing, tuning and regulation require skills based on years of experience. For these reasons the piano is still handcrafted in many respects.

The prospective buyer of a piano who, relying upon his own judgment, attempts to select an instrument soon discovers that very many arguments may arise to perplex him in his choice. As a rule, and with rare exceptions, it is wise to buy of local dealers to whom you can, at any time, have access should there arise necessity for explanations or advice. In dealing with the local piano dealer, do not begrudge him a fair profit. The piano dealer is familiar with the instruments he carries, and if he is a man who is honest and reliable, you may depend upon what he tells you concerning them.

The buying of a used or restored piano can also be a very gratifying experience. 1. The price is usually much lower then a new one. 2. In most cases if the dealer or rebuilder offers a warranty on the used or restored piano. Make sure you ask them what type of warranty they'll offer, This way you'll be protected against any defects the piano might sustain. 3. you be able to have technician (Tuner) voice the piano to suit your needs. 4. With purchasing a Restoration Piano (Not completed yet) you'll have the choice of color that matches your home and individual taste! I classify this as Custom.

Having once decided upon your piano, do not permit yourself to be disturbed by the contradictory talk of any other person who may decry your choice or declare that you have not made a good bargain. In ninety-nine out of every hundred cases, discontent is the result of disappointment born of a competitor's defeat, and such attempted interference is unworthy of consideration.

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